The following high-CPU stress test query gave an interesting result. SYSCOLUMN contains only 2013 rows.

12.0.1.3298
SELECT COUNT(*)
FROM SYSCOLUMN AS A
CROSS JOIN SYSCOLUMN AS B
CROSS JOIN SYSCOLUMN AS C;
There was an error reading the results of the SQL statement.
The displayed results may be incorrect or incomplete.
Value SUM() out of range for destination
SQLCODE=-158, ODBC 3 State="22003"

The first query used 8 CPUs, and took 622 seconds to fail... whether it was "finished" or not is unknown, but it probably was getting close since it had been using fewer and fewer CPUs for the last minute or so.